5.45 For U.S. live births, P(boy) and P(girl) are approximately 0.51 and 0.49, respectively.a According to a newspaper article, a medical process could alter the probabilities that a boy or a girl will be born.

Researchers using the process claim that couples who wanted a boy were successful 85% of the time, while couples who wanted a girl were successful 77% of the time.b Assuming that the medical process does have an effect on the sex of the child: aSource: Bureau of the Census, Statistical Abstract of the United States 2009, p. 64. bSource:

Steve Twedt, “Boy-Girl Selection Available Soon Here,” Pittsburgh Press, December 31, 1987, pp. 1, 10.

a. Without medical intervention, what is the probability of having a boy?

b. With medical intervention, what is the conditional probability that a couple who wants a boy will have a boy?

c. With medical intervention, what is the conditional probability that a couple who wants a girl will have a girl?